In artificial selection, humans provide the selective pressure for species to change and shape the evolution of various breeds. what provides the selective pressure in natural selection?
a) the environment
b) the degree of natural genetic variation in a population
c) disease
d)scientifically trained humans

a) The environment.

Explanation: Natural selection is one of the forces of evolution. Natural selection occurs when individuals in a population have a different reproductive success in certain environment. For example, imagine a mosquitoes population in a insecticide-free envrionment, the non-resistent mosquitoes will be more succesfull that the resistant ones. But when there's insecticide in the environment, the resistent mosquitoes will be more successfull that the non-resistent ones, because they die.

4.) metal

"-the movement of carbon from the nonliving environment into living things and back to the environment

-carbon is the essential component of proteins, fats, and carbohydrates (which make up all organisms)

-carbon exists in air, water, and living organisms

-producers convert carbon dioxide in the atmosphere into carbohydrates during photosynthesis

-bacteria in the atmosphere cycles through the system in filtration units

-in cellular respiration, carbon is released back into the atmosphere as carbon dioxide

-some carbon is stored in limestone (forming one of the largest "carbon sinks" on earth)

-largest carbon reservoir on earth= limestone

-carbon stored in the bodies of organisms as fat, oils, or other molecules may be released into the soil or air when the organism dies

-this may form deposits of coal, oil, or natural gas (fossil fuels, which increased the atmospheric carbon dioxide)

-fossil fuels store carbon left over from bodies of organisms that died millions of years ago

-they are located in the surface of earth, deep within the earth and beneath the ocean floor."    

kelp are large brown algae that live in cool, relatively shallow waters close to the shore. they grow in dense groupings much like a forest on land. these underwater towers of kelp provide food and shelter for thousands of fish, invertebrates, and marine mammal species.

e) all of the above